#15 Enforce Referential Integrity

[Mike Kelly]

Currently, there is no enforcement of referential
integrity with regards to the scheduler data. For
example, if an event requires slot "Guitar" and the
user subsequently deletes the "Guitar" slot type from
the Slot Types tab, the application does not
automatically delete the Guitar slot from all events
that reference it. Here is a list of the data
relationships that exist in the scheduler application:
Event->SlotTypes (one to many)
Resource->SlotType (one to many)
ResourceConstraint->Resource (one to one)
ResourceConstraint->Event (one to many)
FixedAllocation->Event (one to many)
FixedAllocation->Resource (one to one)
FixedAllocation->SlotType (one to one)

The above relationships show that modifying a
SlotType, Event, or Resource can cause data in other
entities to become invalid. For this reason, a
mechanism for enforcing referential integrity should
be implemented to ensure that the data never becomes
inconsistent.